While glucose remains the primary cerebral metabolic substrate under normal conditions, shifting to ketone bodies is a common form of metabolic adaptation demonstrated under conditions of increased energy demands or decreased glucose availability. Our laboratory has shown ketones to be effective in reducing cortical contusion volume by 50% following focal traumatic brain injury (TBI) among juvenile, but not adult rats. The age-dependent neuroprotection of ketones makes it relevant to pediatric TBI, which is the #1 cause of death and disability among children under 15 years of age in the US (Gotschall et al. 1995). The central hypothesis of this proposal is that cerebral ketone metabolism will improve TBI-induced cerebral energy crisis and reduce cell loss in an age-dependent manner and that maturational differences in cerebral transport of ketones accounts for this age effect. The following proposal is directed at 4 specific aims: (1) Histological, functional and behavioral analysis will be used to determine the effectiveness of ketogenic therapy after injury in different ages. (2) Immunohistochemistry and westerns will be used to determine the whether age-related differences in neuroprotection are due to age-dependent upregulation of ketone transporters (MCT) (3) Infusion of monoclonal antibodies to block the vascular endothelial growth factor (VEGF) receptor will be used to determine whether VEGF is the signaling mechanisms for MCT upregulation. (4) Ex-vivo 1H-NMR and 31P-NMR spectroscopy will be used to determine whether the mechanism of ketogenic neuroprotection is improved cerebral bioenergetics. We believe that the use of ketone bodies as an alternative cerebral metabolic substrate offers exciting therapeutic potential following focal TBI in the developing brain and offers desperately needed treatment options for children with TBI.